Edit

The difference between copy and copy(value),between paste(relative) and paste(ablolute)
Example:
A1 1
B1 2
C1 =A1+B1
A2 10
B2 20
if you copy C1 and paste it to C2,C2 cell shows [30]--=A2+B2
if you copy(value) C1 and paste it to C2,C2 cell shows [3]--3
if you copy C1 and paste(relative) it to C2,C2 cell shows [30]--=A2+B2
if you copy C1 and paste(absolute) it to C2,C2 cell shows [3]--=A1+B1